Telephone system



May 9, 1944. McKlM mmraoua SYSTEM ori inal Filed Jan. '5, 1940 11 Sheets-Sheet 1 INVENTOR By J. B.MC KIM @aM ask TEE v Nut 0 8m vat 3E uu GE y 9, 9 J J. BQM KlM Re. 22,476

' TELEPHONE SYSTEM Original Filed Jan. 5, 1940 lISheets-{Sheet '2 DIS-Mr arr/c5 INVENTOR J. a. M; KIM

A 7' TORNE Y M11179, 1944. J, 5, M I Re. 22,476

- TELEPHONE SYSTEM Original Filed Jan. 5, 1940 11 Sheets-Sheet 3 I'NVENTOR BYJ. 8. MC KIM ATTORNEY May 9, 1944. v

JQEB. MGKIM 11 Shefs-Shegt 4 'nvvE/vr'o L B :18. Mc KIM y 1944 J. B. Mm Re. 22,476

TELEPHONE SYSTEM Original Filed Jan. 5, 1940 11 Sheets-Shaet 5 //v VENTOR ATTORNEY v May 9, 1944. J. B. McKlM I TELEPHONE SYSTEM Original Filed Jan. 5, 1940 11 Sheets- Sheet e INVENTOR J 8. MC K/M 696 M A 7' TORNE Y May 9, 1944. -J B. MOKIM Re. 22,476

' I TELEPHONE SYSTEM Original Filed Jail. 5, 1940 11 Sheets-Sheet '7 INVENTOR 8y .1 8. Mc KIM ATTORNEY y 1944- J. B. mm Re. 22,476

TELEPHONE SYSTEM v Original Filed Jan. 5, 1940 11 Sheets-Sheet 8 IN VENTOR J 8. Mc KIM ATTORNEY May 9,1944. J. B. MGKIM Re. 22,476

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CUTE RELAY I I'm.-

ROUTE RELIY MARKER MARKER SEA/DER ATTORNEY y 1944- J. B. McKlM Re. 22,476

TELEPHONE SYSTEM Original Filed Jan. 5, 1940 ll Sheets-Sheet 10 ATTORNEY May 9, 1944. MCKIM TELEPHONE SYSTEM Original Filed Jan. 5, 1940 11 Sheets-Sheet 11 IN VE N TOR J 8. Mc KIM 6P6. M

A 7' TORNE Y Reissued May 9, 1944 TELEPHONE SYSTEM James B. McKim, East Orange, N. J., assignor to Bell Telephone Laboratories, Incorporated, New York, N. Y., a. corporation of New York Original No. 2,277,600, dated March 24, 1942, Se-

rial No. 312,468, January 5, 1940. Application for reissue July 1, 1942, Serial No. 449,275

20 Claims.

This invention relates to telephone systems and more particularly to switching systems for automatically connecting units of equipment together for telephone connections and supervision.

Switching systems which are automatically responsive to incoming telephone calls have ineluded link structures for connecting units of completed their functions in setting switches or other units of equipment for completing a telephone connection. In the latter method of operation it is often necessary to recall the services of the same link or a, link of like structure in the same group of links one or more times for supervisory purposes after a telephone connection has been completed. The selection and operation of links for supervisory purposes constitute a delay in the continuity of telephone service which with the present invention may be avoided.

An object of this invention is, therefore, to provide channels including a link between the equipments involved in a telephone connection and an operators position, which may be automatically or manually locked for supervision of particular classes of telephone connections and automatically or manually released when the class of the telephone connection requires little or no supervision from this operators position.

A feature of this invention is in a systemof selecting and operating an idle link responsive to an incoming call over a trunk line for connecting the trunk line to a channel in an operators position, in connecting the incoming trunk line to an outgoing trunk line and in controlling the looking or releasing of the link and channel responsive to signals registering the class of the incoming and the outgoing trunk lines involved in the telephone connections.

Another and related feature of this invention is in a system of selecting and operating an idle link responsive to an incoming call over a trunk line for connecting the trunk line to a channel in an operators position, in'transmitting signals between the trunk line and the position channel, in setting a control unit from the operators position for automatically completing a telephone connection and in automatically controlling the looking or releasing of thellnk and channel responsive to the signals registered in the control unit.

Another and releated feature is in a system of automatically controlling the looking or releasing of the link and channel by transmitting class signals from the trunk line to the control unit, responsive to the connection of the link to the position channel and responsive to the connection of the control unit to the position circuit.

Another and releated feature is a system for manually controlling the locking of the link and channel to the trunk line connection for the duration of the call or releasing the link and channel therefrom.

Another feature lies in means responsive to a recall on an established connection for signaling the same operator over a locked link or summoning an idle operator where the link has been released.

These and other features will be discussed more fully in the following description.

To illustrate the features of the invention reference may be had to the accompanying drawings in which:

Figs. 1 to 11, inclusive, when arranged as indicated in Fig. 12 show the detailed structure in which a link and channel may be locked to the apparatus involved in a telephone connection for supervisory purposes;

Figs. 1 and 2 illustrate a distant calling toll office, an incoming trunk, an outgoing trunk, a

plurality of switches for connecting incomin and Outgoing trunks and a distant'called toll office; i

Fig. 3 illustrates a link and a connector for connecting calling incoming trunks and link switches to a link-control circuit shown in Fig. 6;

Fig. 4 illustrates the operators position channe s;

Figs. '7, 10 and 11 illustrate a cordless toll operators position circuit;

Figs. 5 and 8 illustrate a cordless toll position control circuit;

Fig. 9 diagrammatically illustrates an operators position sender, a connector for connecting such senders to one of a plurality of markers and the apparatus of a marker which may be used to disclose the-invention.

GENERAL DESCRIPTION The trunks incoming to a toll office vary in transmission characteristics and also vary in character. Via or termial ringdom trunks incoming from a distant toll ofiice operate from alternating current signals. Other tol1 oflices may use the straightforward trunking system transmitting direct current signals for energizing the incoming trunks of a distant ofiice. Other trunks are known as dial intertoll trunks which are operated from pulse transmitting systems for automatically operating apparatus in a machine switching ofiice. In view of this the trunks involved in a toll connection require dii ferent class of service signaling means depending upon the character of the trunk. Signal transmitting apparatus is included in each such trunk for indicating to the associated apparatus of an automatically operable toll oiiice, the character of the trunk connected to this apparatus in order that the same character of trunks shall or shall not be connected together for transmission purposes, and in order that it shall be determined Whether supervision of the telephone connection is required. The same or different characters 1 of inte'rtoll trunks are connected together depending upon the length of the interconnected toll trunks for completing a telephone connection. It is therefore necessary that the connecting apparatus be guided in the matter of class of intertoll trunk and th transmission characteristics of both interconnected trunks. In the sys tern disclosed, such information is automatically available responsive to the connection of an incoming trunk with the connecting apparatus and responsive to the registrations for selecting an outgoing trunk tea loo'aloi distant office.

A call from a distant o'fiice actuates the apparatus of the receiving toll office .by signals, which automatically energize the apparatus of a link for connecting the intertoll trunk such as disclosed in Figs. 1 and 2 with a cordless toll operators position, such as disclosed in Figs. 7, and 11. An idle link channel is chosen by the energization of the link-control circuit of Fig. 6 which selects an idle channel, Fig. 4, entering one of a plurality of cordless toll operators positions. There are ordinarily a plurality of channels entering each position. Each channel is connected to a secondary link switch, such as switch 302 or 303. These are interconnected to a p'lurality of primary link switches available to the calling incoming trunks. By means of cross-wiring these secondary switches may be associated through one of a plurality of primary switches with the calling incoming trunk thus an idle channel of a position may be actuated by the link-control circuit, Fig. 6; and connected by this link-control circuit through a secondary and primary link switch which are also actuated by the link-control circuit. The operation of the link switches connects the apparatus of the channel with the apparatus of the calling in coming trunk circuit causing the energizing of apparatus in both the channel circuit and the calling incoming trunk circuit. The energ'ization of this apparatus is successively interacting which adjusts the incoming intertoll trunk circuit, Figs. 1 and 2, and adjusts the apparatus of the channel, Fig. 4. and the position appar s, Figs. '7, 10 and 1-1; for successive cooperative sig- IIEJSi- The apparatus oi-the channel and pos tion circuit is adjusted for receiving class of trunk line signals from the incoming trunk circuit. The incoming trunk circuit is adjusted for transmitting these signals. The operation of the position apparatus progresses to a point where signals are given to the cordless toll operator 1nciuding atone signal to indicate to this operator the character of "call to be answered.

The apparatus of the position control circuit, Figs. 5 and 8, is energized including a start circuit for the sender 95E Registrations are made in the sender by the cordless toll operator according to code designations given to her by the calling party at station I60. The sender energizes a marker connector Bill for associating an idle marker therewith which receives code registrations from the sender covering the distant toll office or station to which the call should be routed, the character of the trunk lines, the class of the call and the character and class of the incoming trunk line. The registrations are used for selecting an outgoing trunk of a particu-- lar routing having the characteristics required for the type line connection to be made.

Circuit combinations are made in the marker by apparatus operated in accordance with the foregoing registrations which control operations in the sender and the position control circuit when the marker is in the process of releasing. The circuits energized determin whether a link and channel is to be connected between the incoming trunk and position channel apparatus for the duration of the telephone conversation or whether this apparatus shall be released. When supervision is to be maintained over a telephone connection during the period of conversation, circuits are established in the position control circuit for energizing a particular relay in the incoming trunk circuit. The energization of the latter relay establishes. a locking path for the link and a. locking path for particular apparatus in one channel of the position which is associated with this link connection. The position channel and the link is thus locked for maintaining supervision of the telephone connection. Energi'zation of apparatus in the position control circuit by a circuit combination in the marker also energizes a relay in the. incoming trunk when no supervision is required. In this case the channel and link switches are released and may be associated with other incoming trunks for serving other incoming calls. When the link is locked to a channel, only one relay in the channel is kept operated for associating signal paths between the posit-ion and the incoming trunk circuit so that the toll operators position signals may be actuated at any time when either the calling or called parties require the attention of the cordless toll operator. When the link is not locked to a channel, the relay operated in the incoming trunk permits either the calling or the called party to operate an idle link to signal an idle operator.

In addition to the arrangement for locking a link and channel automatically from the marker, a second arrangement is used for locking the link and channel manually by the energization of a position key which energizes relays accomplishing the result manually which; is accomplished automatically by the marker. The actual locking of the link is only accomplished after the marker has completed the selection of the outgoing trunk and 1 set the switches fo the connection between this outgoing trunk and the incoming trunk, As before, the marker in the process of releasing energizes. apparatus which completes circuits for locking the link by the energization of particular relays in the position control circuits. This manner of locking the link manually is placed under the control of the marker in order that apparatus operations take place in proper sequence.- I

DETAIL DESCRIPTION In the present disclosure the distant ofilce I is connected to the automatically operable toll ofiice illustrated in the drawings Figs. 1 to 11, inclusive, by a ringdown intertoll trunk which is energized by transmitting ringing current from oflice I00 over conductors I35 and I36 to the incoming trunk, Figs. 1 and 2. After the distant operator in oilice I00 has completed setting apparatus for the connection, this ringing current is applied automatically or manually to conductors I35 and I36 which is transmitted through the winding of alternating current relay I03 energizing this relay. The energization of relay I03 releases relay I04 which is normally energized from battery through its winding to ground on the contact of relay I03. The release of relay I04 establishes a circuit for operating the incoming trunk relay 202 over a circuit from battery through the winding of relay 202, contact 2 of relay I04, contact I of relay III, contact 3 of relay 203 to ground. Relay 202 in operating establishes a locking circuit for itself through its contact 3, contact 1 of relay III to ground through contact 6 of relay 203. When ringing current is disengaged from the trunk conductors I35 and I36, relay I03 releases which reenergizes relay I04. A circuit is thus established for relay [I3 from battery through its winding, contact 5 of relay H2, contact 2 of relay I04, contact 3 of relay 202, contact 'I of relay I I1, contact 6 of relay 203 to ground. Relay H3 is locked through contact 4 of relay 20I, contact '5 of relay II3 to its operating ground on contact 6 of relay 203. The operation of relay II3 now establishes a start circuit for a link which associated the incoming trunk and the operator at oflice I00 with the cordless operator whose telephone apparatus is shown in Fig. 11 of this disclosure. This linkstart circuit may be traced from ground on contact I of relay II4 through contact 2 of relay II3, contact I of relay IIZ, lead 320, contact of relay 3I2, winding of link-start relay 3 to battery. The link-connector and link-control circuit is shown diagrammatically and reference is made to the patent application to King et al. Serial No. 295,010, filed September 15, 1939, issued as Patent No. 2,236,246, March 25, 1941, or the patent application to Busch et a1. Serial No. 295,012, filed September 15, 1939, for a complete disclosure of this link-connector and linkcontrol circuit.

Link connector The energization of the link-start relay 3 establishes an obvious circuit for a link-connector selecting relay 3l6 which operates a multicontact relay such as 3|! for connecting a large number of leads from an idle link-control circuit, Fig. 6, to the incoming trunk circuit, Fig, 1 and Fig. 2, to a plurality of toll positions, Fig. 4, and to a plurality of switches, Fig. 3. There are a plurality of link-control circuits, Fig. 6, which are small compared to the large number of switches, Fig. 3, and the large number of position channels, Fig. 4. Consequently, as noted in the aforementioned patent applications, it is necessary for a link connector to find an idle linkcontrol circuit before operating the multicontact relay 3I1 to connect these different units together. The switches 300 and 30I represent a single horizontal level in two verticals of a primary link cross-bar switch connected to an incoming trunk circuit.

Switches 302 and 303 are known as secondary switches of which there are a large plurality connected to a large plurality of channels in a plurality of cordles toll positions. The ones shown are difierent horizontal levels on different verticals of the same or different cross-bar switches. The function of the linkcontrol circuit is to test a plurality of channels associated with a plurality of cordless toll positions to obtain an idle channel and the services of the toll operator in the cordless position to which this channel is connected. In view of the fact that each channel is connected to a different horizontal level of secondary switches, such as 302 and 303, the test ofthe channel determines the secondary switch to be used. Each incoming trunk appears on at least one horizontal level of a primary link switch which may be reached from different secondary link switches through different verticals on'this primary link switch. The hold magnets for the primary and secondary switches, which constitute a channel, are connected in multiple as shown and operate together. An idle channel in a position having an operator in attendance has battery on lead 340 and ground on lead 34L Ground is placed on lead 34I by the operation of relay 40I actuated when relay 'IOI is actuated. Relay MI is only actuated when an operator is serving the cordless position. The circuit for relay it! may, thus, be traced from battery through its winding, contact I of individual channel relays MI, 420 and 402, normal, jack H04 which has its contactclosed when the telephone o-perators headset plug I I06 is inserted therein, key 505, to ground on contact I of relay 500, Relay 40I has as many contacts thereon as there are channels in the position and, therefore, its operation makes all channels idle which are not in use. The release of this relay makes all channels busy. This will be seen from the description of the channel apparatus.

Link and link-control circuit The link control circuit, Fig. 6, is used for selecting an idle channel from large plurality of channels entering cordless toll positions. The control circuit is associated with channels which are connected to certain levels of the secondary cross-bar switches shown in the right-hand portion of Fig. 3. These control circuits are in an incoming group arranged to serve the calling incoming trunks for testing the channels of the position and operating switches which connect a calling incoming trunk with an idle channel. The operation of start relay 3| 1 establishes circuits for energizing a connector unit for controlling the association of a calling incoming trunk with an idle link-control circuit. The switches 300 and 3M comprise a portion of a primary link switch. Each switch of this character ordinarily has ten separate levels and a large plurality of verticals. In this instance only one is shown which is arranged to connect the calling incoming trunk to a secondary switch by the operation of a select magnet and a hold magnet. In practice the incoming trunk may be associated with various secondary switches 302 and 303 through a number of different verticals on the primary switch, making a large plurality of choices of apparatus for extending acall from the incoming trunk to the apparatus of the channels in the toll office switchboard. The secondary switches 302 and 303 may be on a single crossbar switch or on separate cross-bar switches depending upon the choice of connection which is best suited for use. The secondary switch points shown may therefore be considered-as one level of any vertical on a single cross-bar switch or one-level of a vertical on any of a plurality of cross-bar switches.

The multicontact relay 3H and the multicontact relay 3!! and the relays shown in the lower portion of Fig. 3 constitute an arrangement for giving an incoming trunk a plurality of choices in obtaining the services of a link-control circuit, Fig. 6, which may be associated therewith by the operation of the multicontact relay 3. The control circuit associated with a relay, such as 317, must test idle before it is seized. There are a pluralityof multicontact relays 313 for each incoming trunk circuit. This plurality of relays are connected to a plurality of relays 3!! which are interconnected when strapped as shown. There are a plurality of relays, such as 311, for each connector extending between the contacts of relays 3H and 3H. Each control circuit has a representative relay in each connector so that any one of the control circuits may be associated when idle with any of the connectors between a group of trunks and the control circuits. The operation of start relay 3| l by a circuit as previously established from the incoming trunk initiates the selection of an idle control circuit. A circuit is first established from battery through resistance aw, contact of start relay 3i I, winding of relay 3l5 to ground where a chain of relays, such as sit, is used to prevent the actuation of a connector by more than one trunk and for the select-ionof an idle control circuit. When the control circuits associated with such relays are busy no circuit is established for the relay. The energization of relay 3H establishes an operating circuit for the multicontact relay 3H for seizing an idle link-control circuit.

As previously stated the organization of the link switching arrangement and the control circuit is such that a choice is made from a large number of channels. In some instances a number of idle channels are simultaneously associated with the control circuit and only one of these is selected. The selection is made by a chain circuit in a secondary switch level selecting circuit $04 in which there are a plurality of relays equivalent to the number of channels which are tested. Relay 635 represents one channel. This relay, however, represents a switch combination associated with different channels, such as secondary switch 382 and primary switch 300 or secondary switch 303 and primary switch 3!, each combination being associated with a diiferent channel. In the same manner a plurality of verticals on the primary switch are connected to verticals on a plurality of secondary link switches. The verticals of the secondary link switches each have a plurality of horizontal levels connected to different position channels. The hold magnet on the vertical of the primary link switch and the hold magnet on a vertical of a secondary link switch are in multiple so that they may be operated simultaneously. The operation of any of the relays 505 indicates that they are associated with an idle channel and the preferred idle channel in the chain of relays, such as 585, is taken for the connection. In practice there are as many contacts on relay 3E4 of the connector as channels which are connected to the control circuit, Fig. '6. These relays are operated for associating the channel equipment with the control circuit to energize apparatus of the control circuit ior selecting the idle channel and for making a test of this idle channel through the contacts of relay 315. This latter test is actually a secondary or double test to make sure that the channel is not seized by another control circuit immediately after it has been found idle by the control circuit being described. The operation of any particular relay, such as 35, determines the secondary switch level to which the idle channel selected is connected and, consequently, the control circuit may energize the switch combination of primary and secondary switches for con meeting the incoming trunk to the channel selected.

A group of links and link-control circuits serve a plurality of groups of trunks which may be known as subgroups of trunks within the larger group. When a particular trunk within a subgroup of trunks actuates a link circuit, it is necessary to identify the subgroup with which it is associated. The link-control circuit is therefore provided with a plurality of relays 8% equivalent to the number of trunk subgroups served through the contacts of the associated connector relays. In this instance it may be assumed that a circuit is established for the group relay sec to show the subgroup of trunks requiring servi-c A circuit is now established for relay 313 beionging to this subgroup. There are a plurality of trunks in each subgroup served by the same start relay 311. These are represented in the control circuit by a plurality of relays, such as relay iiiili. It will be remembered that a start ground was placed on conductor 32!! of the incoming trunk when the start circuit was established. This ground operated relay 3H but at the same time extends ground through a plurality of contacts on relay 3l2 and a plurality of contacts on relay 3l'3. There are as many contacts on relay M2 and 31.3 as there are trunks in a subgroup. This plurality of contacts is represented by one contact on relay 3l2 and contact 5 on relay 3L3. There are as many trunk relays 685 as there are trunks in the subgroup, all of which are initially operated from the start ground extending through one of the contacts on relay M2 and relay M3. The operation of these relays associates ground through a chain circuit, such as shown on contact 2 of relay 6%., contact 6 of relay 343, winding of relay 312 to battery. The energization of relay 3L2 releases the start relay 3!! and open the leads from all trunks except the calling incomingtrunk. The start ground therefore extends through only one contact of relay 313 through the winding of a relay 6B9 representing the calling incoming trunk. This relay remains operated and the relays associated with the other trunks are released. Relay 695 looks over the operating circuit traced to the start ground. The operation of the relay establishes the level of a primary switch to which the incoming trunk is connected and immediately establishes a circuit for the select magnet 364 for this level of the primary switch. This circuit may be traced from battery through contact I of relay are, contact Z of relay 3H, winding of select magnet 304 to ground. The operation of select magnet 304 connects ground through its contact and through contact 3 of relay 3, winding of control circuit relay Gill-1 to battery energizing the iatter relay. The operation of relay iiilil now establishes a circuit to determine the class of service required by the incoming trunk. This class of service is determined by the operation of one of a plurality of relays, such as relay B03, in the control circuit. Since, in this case, only one class is required, a

circuit is shown established for relay 603 through the apparatus of the incoming trunk circuit. This circuit may be traced from ground through contact 4 of relay 600, contact of relay 3|l, contact 3 of relay 3|3, conductor 330, contact 9 of relay 202 of the incoming trunk circuit which is operated thence over lead 33], contact 4 of relay 3|3, contact 8 of relay 3", winding of class relay 603 to battery. The operation of this relay connects battery through its contact, contact II of relay 3|l, contact of relay 3|3, winding of relay 3|4 to ground. As previously stated there are as many contacts on relay 3|4 as there are channels associated with the control circuit. An idle control circuit establishes circuits for one or more relays, such as 605, in the control circuit. This circuit may be traced from battery through the winding of relay 605, contact |3 of relay 3", contact of relay 3I4, lead 34|, contact 2 of relay 4 to ground on contact of relay 40L The establishment of this circuit indicates an idle channel in a switchboard position attended by an operator since, as previously described, relay MI is only operated when the operator is attending the switchboard position circuits. The operation of relay 605 establishes a circuit for operat ing the double test relay 3|5 as shown from battery through contact of relay B05, contact l4 of relay 3", winding of relay 3|5, to ground. Since relay 605 is individual to the idle channel selected, the testing circuit of the control circuit is applied to the apparatus of this channel. This testing circuit comprises delicate apparatus which may operate if two control circuits are associated with the same channel. This testing circuit has been limited to relay |0 which is now associated with the idle channel over a circuit from 24-vo1t battery through its winding, contact 4 of relay 605, contact 15 of relay 3||, contact of relay 3|5, lead 340 to 48-volt battery connected with contact of channel relay 4| I. The operation of relay 605 also establishes a circuit for the select magnet associated with the level of the secondary switch connected to this idle channel. This circuit may be traced from battery through contact 3 of relay B05, contact 4 of relay 3|'| through ground through the select magnet 3|8. The operation of the select magnet connects ground through its contact, contact 5 of relay 3|I, relay 602 to battery. The operation of relay BID indicates that no interference has been encountered in the selection of the idle channel and establishes a circuit for relay 606. All of the elements to be used have now been tested and the mechanism associated therewith energized. The operation of the select magnets of the primary and secondary switches energizes relays EM and 602. The test of the channel associated with the secondary switch was made by the, energized relay 605. A circuit mayv therefore be established at this time for energizing the hold magnets of this switch combination for connecting the incoming trunk with the selected channel. This circuit may be traced from ground through the contacts of relays B02 and 60!, contact of relay 606, contact 2 of relay 605, contact 5 of relay 3||, contact 2 of relay 3I3, to battery through the hold magnets 305 and 301. The operation of the secondary switch 302 establishes a circuit for channel relay 4 from battery through its winding, contact 3 of switch 332, contact 2 of relay 3|3 thence through contact 5 of relay 3H, contact 2 of relay 605, contacts of .relays 055, Bill and 602 to ground. A circuit is also established for relay 4I0 from battery through its winding, contact 2 of relay 403, contact 1 of switch 302, contact of switch 300,- lead 32|, contact 2 of relay 2, to ground through contact I of relay H3. The operation of relay 4| I disassociates 48-volt battery from the testing circuit lead 340 and connects ground therewith. This causes a reversal in the testing circuit of the control circuit releasing relay 6|0 which is necessary for the release of the control circuit. The operation of relay 4 removes ground from the test lead 34| and this lead now remains open. This causes the release of relay B05 in the control circuit which enters into the release of the control circuit. This control circuit will now be released as soon as the trunk start circuit is opened.

Position channel The operation of relay 4 establishes obvious circuits for lighting the busy lamp 401 and the guard lamp 406.. Relay 0 establishes an obvious circuit for lighting guard lamp 409. The operation of both relays 4I0 and 4H establishes a circuit for energizing the channel preference relay 402. There are as many relays, suchas 402, as there are channels in a cordless position. These relays, such as 402, 420 and HI, are in a chain circuit to prevent seizure of more than one channel at a time or seizure of one channel in a position when another channel is connected to the operators headset. The operating circuitfor relay 402 may be traced from battery through its Winding, contact of talking relay 4| 0, contact 3 of relay 4| I, contact 2 of relay 402, contact I of relay |0| to ground. Other operating circuits for relay 402 are also established through contact 2 of the monitoring relay 4|2 when operated or through contact 4 of the backward relay 4|3 when the latter relay is operated. Relay 402 in operating establishes a locking circuit for itself from battery through its winding, contact I ofrelay 4 0, contact 3 of relay 4| to ground through its contact 2. This relay also opens the operating circuit for relay |0|. extending through its contact I and establishes a circuit for relay M3. The circuit for relay 4|3 may be traced from battery through its winding, contact of relay 402, contact of the operator's jack H04, contact of emergency key 505, contact of backward release relay 500 to ground. The release of relay |0| opens a circuit for relay 40| .to cause its release so that all channels of the position are made busy during the period required by the operator in serving a call entering her position.' This includes supervising operations, such as talking to either a calling or a called party or The operation of position as a preparatory signal in advance of a tone signal given to the operator a fraction of second later. cuit for relay 4| and a holding ground circuit through its contact 3 and contact 4 of relay 4H for the hold magnets 305 and 301. The switches 300 and 302 are, therefore, no longer dependent upon the link-control circuit for maintaining their holding circuit. The operation of relay 403 Relay 4 I 3 establishes a locking circloses circuit pathsforthetalking and signaling conductors from the trunk. through the contacts of the link switches to the cordless position apparatus, opens the locking circuit for relay ll which restores to normal and closes .an operating path for relay 404. The circuit for relay 034 is established from ground on contact 2 of relay its in the position control circuit, contact 3 of relay 165, contact I of relay 803, contact 1 of relay 59H, contact I0 of relay 403., winding of relay 4.04 to battery. The latter relay locks to its. operating ground. The operation. of relay .433 now energizes relay I I2 in the incoming trunk circuit for opening the link-start circuit extending to relay 600 of the link-control circuit. The circuit for relay II2 may be traced from ground on contact I of relay 504, contact I of relay 503, contact 6 of relay 403, contact l2 of switches 392 and 300, lead 332, contact 2 of relay II-I, contact 3 and the winding of relay I I2 to'battcry. Relay I I2 establishes a locking circuit for itself to ground on contact 6 of relay 203 over a circuit including contact 4 of relay I I3, contact 2 of relay I33, contact 3 of relay 2'02 and contact 1 of relay 1. The operation of relay II2 removes the start ground from lead 320 which extended through its contact I and causes the release of relay 6213 in the link-control circuit. The release of relay 633 causes the release of relay 608 which releases relay 3.I3. The release of relay 313 opens the locking circuit for relay 3I6 which releases and, in so doing, releases relay H1. The release of relays 3I3'and 3I1 opens the circuit of all relays in link-connector and link-control circuits. The link connector and link-control circuits may now serve other calls entering the telephone office. As previously stated, a ground is supplied from the position circuit for maintaining the hold magnets 305 and 301 operated and, therefore, the switch connection between the position channel and the trunk remains established.

Class of trunk signals The operation of the previously described relay M3 in one of the channels connects ground from its contact I through the winding of position relay 102 to battery. The operation of the latter relay connects ground through its contact 2, contact 5 of relay 500, contact I of the class relays III1 and I I I9 to battery through the winding of class relay 109.. Relay 10!! operates and connects leads H5 and 1|..B through its contacts I and 2 to the windings of class relays II2I, H22, I I23 and I I24 to battery through resistances H25 and H26, respectively, thus starting class determination. The ground from contact 2 of re lay 192 also extends through contact 5 of relay 500, contact 3. of relay 109, winding of relay 1l0 to battery. Relay 1I.0 opens leads H0 and H9 extending to the operator's telephone circuit and establishes an operating circuit for relay 1 which may be traced from battery through the winding of relay H I, contact I of relay 1 I0, contact 5 of relay 50.0, contact 2 of relay 102 to ground. Relay 1] I, in operating, establishes a locking circuit through its contact 6 to the operating ground. The class signalsare transmitted to the position circuit in order that the position sender and the marker may be guided by the character of incoming intertoll trunk connected therewith. The incoming trunks which are connected to the cordless position for toll or terminating connections may be of the ringdown or straightforward type from distant toll offices or from tandem ofiices and they may vary in transmission characteristics. For example, a via intertoll outgoingtrunk must be selected by the marker. for a call from a distant toll oflice which shall be routed. outgoing to another toll oilice. On the other hand, if a call is .for a connection which may extend from one toll ofllceto this toll ofiice and is terminated in a local subscribers station, it is not necessary to use a toll trunk of the equivalent transmission characteristics as used for the via connection. There are also trunks which are of these characteristics in so far as transmission qualities are concerned but which have different signaling devices, such as the difierence in signals between the straightforward intertoll trunk and the ringdown intertoll trunk. The class signal in each case indicates the characterof the trunk by associating a grounded circuit which may or may not. have resistance in series therewith and open circuits in various combinations with the class relays. These are connected from the trunk circuit, Fig. 2, through the contacts of relay 20I or a similar relay in a different intertoll trunk circuit over leads 333 and 334 through the cross-bar switches of Fig. 3, contacts 1 and 8 of relay 403 to the class relays II2I, H22, H23 and H24. These relays are marginal and, consequently, operate according to the resistance in series with the energizing circuit. The following are examples of some combinations that are made. If a grounded resistance is connected to lead 333 and lead 334 remains open, relay II2I operates which energizes relay II I1. The latter relay is operated from battery through its winding, contact of relay IiZI to ground on contact II of relay 1. Relay I I I1 when operated locks to this operating ground. When lead 333 is connected directly to ground with no resistance in series therewith, relays II 2| and H22 are operated which causes the operation of relays II I1 and II I8, both looking to ground on contact II of relay 1| I. The same combination is used where lead 334 is either connected directly to ground or grounded resistance which operates relay H23 in one case and both relays H23 and H24 in the. other case. This causes the operation of either relay III9 or both relays I I I9 and I I20 which look in the same manner as described for relays III1 and IIIO. Varied combinations are used throughout to indicate the characteristics of the different trunks.

These indications are later transmitted to the sender and marker and are used for establishing circuits as will later be described.

Splitting relay It will be noted that when any class determination is made the operating path for class relay 109 is opened by the operation of either relay III1 or III 9, thus causing the release of relay 109. This relay is slow to release to allow time for class determination. The release of relay 109 operates relay 106 and releases relay H0. The circuit for relay 106 may be traced from ground through contact 5 of relay H I, contact, 5 of relay 109, contact 0 of relay 500 to battery through the winding of relay 105. During the foregoing operations a check is made for the sleeve holding ground provided by the incoming trunk circuit when relay 232 was operated as previously described. If this ground has been properly associated with the sleeve lead, a circuit is established for relay 108 which may be traced from battery through the windings of relays 108 and 101 in series, contact 5 of relay 504, contact 6 of relay 516, contact 5 of relay 00I, contact 4 of relay 8&3, contact 1 of relay 4I3, contact 3 of the link switches, Fig. 3, thence over lead 329'through contact 9 of relay 201 and contact 4 of relay 202 to ground. Relay B is locked to ground on contact 8 of relay 111. This holding ground later serves to hold the switch hold magnetsoperated on a connection which has been established when the splitting relay 201 is operated for talking to the called party. Relay 101 is a polarized relay and does not operate unless the circuit traced is associated with a connection which has already been established. If this circuit is associated with an established connection, battery through the switch hold magnets will operate relay '18! to ground on contact 8 of relay III or to ground on contact 2 of relay 106. When this relay is energized a circuit is established for relay 8110 through the contact of relay I01, contact 4 of relay HI, contact 2 of relay I10, contact 5 of relay 59%) to ground on contact 2 of relay I52.

ing lamp I 010 to show that the position is associated with an established connection. Relay 101 is also used in connection with the release of the position apparatus. The operation of relay 105 over the circuit previously established associated ground with lead in to operate the splitting relay Ztl of the incoming trunk over a circuit which may be traced from ground on contact 3' of relay 500 through contact I of relay 106, lead 111, contact e of relay 403, contact 6 of switches 302 and contact 4 of relay 112, winding of relay 281 to battery. Relay 201 in operating establishes a holding circuit for relay 113 from battery through its winding, contact 4 of relay 201, thence to the operating ground for relay 201. Relay lit remains operated after the release of relay 201 over a circuit traced from battery through the winding of relay H3, continuity contact of relay 201, contact 5 of relay I13, contact 2 of relay 1M, contact 3 of relay 202, contact 1 of relay Ill, contact 5 of relay 203 to ground. This splitting relay 2%! is released when conversation between the operator and the calling operator has ceased and part of the position apparatus is released. At this time, however, the splitting relay 201 is operated to disassociate the inward and forward ends of the trunk and associate the forward end with the cordless position circuit for signaling purposes and for conversation between the operators. The forward relay,

such as (Hi4. of the position channel is operated if no other forward relay in the sequence circuit is operated. A circuit for this relay is established as described when the backward relays 403 and 413 of the channel operate. Relay 404 establishes a circuit for relay 515 over an obvious circuit and the latter relay establishes a circuit for relay 105 which ties the forward and backward portions of the position circuit together for service on the same call. The circuit for relay 105 may be traced from ground through contact 3 of relay 515, contact 3 of relay 803', winding of relay 105 to battery.

Position signals An arrangement of signals is provided which are operated by relay combinations in the position circuit under the control ringdown incoming intertoll trunk circuits, Figs. 1 and 2, or incoming intertoll trunks of other connections which have apparatus responsive to diiferent signals transmitted over the toll lines or trunks. The operation of apparatus in the incoming trunk circuit under different conditions connects bat- The operation of relay 81111v supplies ground to the position circuit for light-' answer.

-ation of all of the above relays.

tery to cliiferent values of resistance over lead 321 to the position circuit. This lead 321 may be traced to the position circuit through contacts I of the link switches 300 and 3112, contact 2 of relay 403 and thence through the windings of marginal relays I014, 1015 and 1016 to ground. The number of these relays operated depends upon the value of resistance associated therewith responsive to calls of different character. For example, when a call is a new call or connection to an outgoing toll trunk, relay 112 is operated which associated resistance in circuit with relays I014, 1015 and I016. The value of resistance 110 is such that only relay 1014 is operated. This establishes a. circuit for relay 1003 from battery through its winding, normal contact of relay 1015, contact of relay 1014 which is operated to ground. This indicates that the call to be answered by the cordless operator is a new call. In this case the apparatus of the position toll circuit will establish a circuit for relay 1011. In. the case of a recall from the calling distant operator, the same circuit will be established with the exception of the circuit for relay 1011. In the case of a recall, relay B00 in the position control circuit is operated and there will be no circuit for relay 1011. Therefore, on a recall a circuit is established to light lamp 1010 and a distinctive tone is transmitted to indicate this type of call. When a manual recall is made from a called office, circuits are established for relay I12, 201 and 204 of the incoming trunk circuit, Figs. 1 and 2. The operation of the above three relays connects resistances 222 and 110 in multiple and these multiple resistances are connected in series circuit with relays 1014, 1015 and 1016. The value of resistance 222 in multiple with resistance 110 is such as to cause the operation of relays I014 and 1015. The operation of both relays 1014 and 1015 establishes an obvious circuit for relay 1002 which lights lamp 10!! and associates a distinctive tone with the operators headset. A different signal is given when the distant called party does not In this case, incoming trunk relays 112 and 20'! are operated which connects resistances 221 and 110 in series with relays I014, 1015 and 1016. The value of resistance 221 in multiple with resistance 110 is such as to cause the oper- The operation of these three relays establishes an obvious circuit for both relays 1002 and 1003 which lights lamp 1012 through their contacts and establishes a circuit for a distinctive tone.

The tone circuit, known as the order tone, for indicating to the operator that a particular connection has been established which is either a new call, a recall or that the connection desired has not been established. This tone circuit is established by the operation of relays shown in the left portion of Fig. 10 over the control relays I014, I065, I016, 1002 and I003. The operation of either relays Iii-d2 or 1003 indicates to the position operator that the incoming call is from a ringdown intertoll trunk and also establishes a characteristic circuit to the marker. With these relays released circuits are established for indicating that the call is from a straightforward intertoll trunk. In the case where both relays are released, three pulses of order tone are transmitted to both the distant operator and the cordless operator. When only of the above relays is operated, the tone will be transmitted only to the cordless operator. One pulse of tone is transmitted when relay 1002 is operated and two pulses of tone are transmitted when relay I003 is operated.

Position tone circuit The order tone circuit is established from the position control circuitwhich associated ground with lead 5020 through contact of relay i000, lead I000, contact 0 of relay I020, contact 4 of relay i050, winding of relay I02I to battery. Relay I OH is the first of a series of operations for energizing and deenergizing the tone circuit. This tone circuit may be traced from tone source I022 through various contacts of relays IOI3, IOI8, IOI9, I020 and I02I, thence through the right winding of tone transformer I005 to ground. The tone is transmitted by induction through tone transformer I005, contacts I and of relay I004 to the talking conductors which in one case extend through contacts I and 0 of relay IIOI and the windings of transformer II02 by induction to the cordless operators headset. As previously stated, on certain calls the tone is transmitted only to this cordless operator but when a call is transmitted over a straightforward intertoll trunk, relays I002 and I003 are both released and the tone is transmitted through contacts I and 1 of relay I003, contacts I and B of relay I002, thence to the contacts of relays IO0I and I000, contacts I0 and II of relay 413 to the trunk conductors.

The sequence of operations of the tone relays is as follows: Relay I02I operates to ground on conductor I030. As previously traced, the operation of this relay establishes a circuit for relay I020 to the same ground through contact 5 of relay I02I and contact 4 of relay IOI9. The operation of relay I020 closes the tone circuit through its contact 3 from the tone source I022 and the tone coil I005. Relay I020 looks through its contact 5 and contact 4 of relay IOI0 which opens the operating circuit for relay I 02! and the latter relay releases. A circuit is thus established for relay mi 9 through contact 0 of relay I 020 and contact 3 of relay I02I. The operation of relay IOI9 opens the tone circuit for ending the first impulse of tone. The circuit for relay I020 is opened by the operation of relay I 0| 9 causing its release. A circuit is now established for relay IOI8 through contact I of relay IOI0 and a locking circuit is established through its contact 3. This sequence of events again establishes an operating circuit for relay I02I through contact 6 of relay IOI9 and contact 4 of relay I020. A second impulse of tone is started by again closing the tone circuit through contact I of relay I02I, normal, contact I of relay i020, contact I of relay IOI8, which is operated, and through coil I005 to ground. The circuit of relay IOI0 wa opened by the operation of relay I02I and releases. A circuit is thus established for relay I 020 which is the same as the circuit over which it was previously operated. A circuit is also established for relay IOI3 through contact 2 of relay IOI0, which is held locked, contact 2 of relay I020 and contact I of relay IOI9 to the original ground as traced. Relay IOI3 locks to this same ground. The operation of relay I020 opens the circuit for relay I02I, causing its release and opening the tone circuit which ends the second pulse of tone. A circuit is now established for relay I 0| 9 which circuit is the same as previously established for this relay. This closes the tone circuit for a third impulse of tone and opens the circuit for relay I020. This is the last tone circuit'established and may be traced from the tone source I022 through contact I of relay I02I, contact 2 of relay IOI0, contact 3 of relay i0I3, winding of the tone coil I005 to ground. A relay i02l is now energized through contact 0 of relay HHS, contact 4 of relay I020, over leads i030 and I020 to the original ground. The operation of relay I02I opens the tone circuit and terminates the third impulse of tone and also establishes a circuit for relay I000 through contact I of relay IOI3, contact 2 of relay I020, contact 2 of relay I02I to the original ground. Relay I000 in operating establishes a locking circuit -for itself through its contact 0 to ground over lead I020. The operation of relay I004 separates leads I020 and I030 at its contact 4, thus releasing all of the relays which were held to this ground including [M3, N8 and I02I.

The foregoing describes the operation of the tone circuit for transmitting three tones which isthe maximum used in this circuit arrangement. As previously explained, three tones are used when the toll call is incoming over a straightforward trunk and may indicate a new call over this trunk or a recall by the originatingoistant operator. A call from an originating operator over an incoming ringdown trunk actuates relay I003 either when this call is a new call or when it is a, recall from the originating operator. A recall from the called party operates relay I002 and the called party does not answer both relays I002 and I003 but relay I002 is the only one effecting the control of the tone circuit. Under the condition of a new call or a recall from the originating operator, using an incoming ringdown intertoll trunk, the operation of relay I003 causes one pulse to be transmitted to the cordless operator. The talking circuit to the incoming trunk is opened to contacts I and I of relay I003 and thus this one pulse does not reach the incoming trunk. The operation of relay I003 establishes a circuit for relay I004 after one pulse has been transmitted. This circuit may be traced from battery through the winding of relay I004, contact 3 of relay I002 which is normal, contact 3 of relay I003 operated, contact I of relay IOI0 which is operated at this time, and thence to ground over leads I030 and I020 through contact 4 of relay I004. Relay I004 in operating separates leads I030 and I020 and locks through its contact 4 to lead I020. As previously stated, the operation of relay I004 releases the tone actuating relays and ends the transmission of tone after one pulse. The operation of relay I002 on a recall from a called toll ofiice or information operators desk causes the transmission of two pulses to the cordless operator. These pulses do not reach the incoming and outgoing trunks. The operation of the tone circuit relays proceed as previously described until relay I020 operates a second time. A circuit is thus established for relay I004 from battery through its winding, inside contact 3 of relay I002, contact 2 of relay IOI8, contact 2 of relay I020, contact 2 of relay I02I to ground over lead 1030. Relay I004 opens the tone circuit as previously described and looks through its contact 4 to lead I029.

The foregoing indicates the action in the cordless toll operators position circuit both for a new call entering this position as previously described, and for a recall from a distant operator. It is assumed for this description that the distant toll operator in toll office I00 requests a connection to an operator in a distant toll ofiice over a via intertoll trunk and, consequently, the apparatus of the sender 900 and the marker 9M must be actuated in a manner to actuate the cross-bar switches 282 and 285 for-connecting the incoming intertoll trunk, Figs. 1 and 2, with an outgoing trunk 280 extending to office 28l, disclosed diagrammatically in the right portion of Fig. 2. Reference is made to the Patent 2,235,246 to King, McKim, Myers, March 25, 1941, for a complete description of thecordless toll position equipment, position control circuit, position sender 900 and marker 90! for operating the apparatus of this ofilce to complete the connection between the incoming intertoll trunk and the outgoing trunk. In order to simplify this description, only the parts which are involved in carrying out the operation of this invention are disclosed and described.

Sender During the foregoing operations which provide a signal to the operator indicating a call has entered the position and the character of the incoming call, a circuit is established for the sender start rela 104 as soon as certain relays are in the following position: Relay I02 operated, relay 500 released, relay H released, relay 1 operated, relay I01 released, relay I operated, and relay 103 released. The positioning of the foregoing relays was established as previously described. The circuit for the sender start relay 104 may therefore be traced from ground through contact 2 of relay I02, contact 5 of relay 50!), contact I of relay H0, contact 4 of relay H I, contact of relay 101, contact 5 of relay I05, contact 2 of relay H33, winding of relay 104 to battery. Relay 104 looks through contact I of relay SIB, contact 5 of position release relay 804 to ground through contact 2 of relay 5l5 which was operated by relay 404. The operation of the sender start relay Hi4 establishes an operating circuit for sender control relay 925 in the sender 900 from ground through contact 3 of relay I04, winding of relay 925 to battery; Relay 925 operates relay 103 from battery through its winding, contact 2 of relay 5| 6, contact of relay 925 to ground. Relay I03 locks to this same ground through its contact I. The operation of the latter relay opens the operation path for the sender start relay 104 which now remains operated under the control of its locking circuit which extends through the position release relay 804, Relay 103 is slow in operation to guard against too rapid seizure of the sender.

The elements of the position sender may be roughly divided with respect to their functions into principal parts, the key-set, the register circuit, the connector control circuit for associating the connector between the sender and the marker and control relays for establishing circuits through the connector to the marker for controlling the operations of the apparatus in the marker, all of which is diagrammatically shown as sender 900.

The position sender is now in readiness to receive registrations from the position circuit. The cordless toll operator upon observing a lamp signal and receiving a tone signal indicating the type call to be answered challenges the distant operator which in this case is a toll operator at toll office I00 and receives the code or code and numerical designation of a wanted party. In

certain cases Where the connection to another distant toll office is desired only the code number is given to the cordless toll operator, When a call incoming from another toll office terminates in the area of the toll office receiving the call, the code designation and numerical designation may be given by the calling toll operator so that a telephone connection can be completed in this area by the cordless toll operator. A large variety of combinations of interconnections between incoming trunks of various character and outgoing trunks of various character are provided. For this reason numerous combinations of call registrations are required both for indicating the character of the calling incoming trunk and the character of the outgoing trunk required for completing the connection. Only sufficient apparatus combinations are shown to carry out the operating circuits of the invention.

The cordless toll operator manipulates the keys of the position key-set for energizing registers in the sender. These registrations in the sender are transferred to the marker after the energization of a marker connector Bill by the sender which associates the sender with an idle marker. There are only a small plurality of markers by comparison with the plurality of senders in this character of toll office and consequently a marker connector is used for finding an idle marker and associating the sender which has been'energized with this idle marker. Registrations are transferred to the marker covering the routing of this connection and the character of the calling incoming trunk circuit. This includes the character of the outgoing intertoll trunk to be used for the connection. The above registrations in the marker are used for completing the telephone connection and for con.- trolling apparatus of the cordless toll position as soon as this connection has been made. This automatically adjusts the incoming trunk circuit to either arrange circuits for placing the telephone connection under the constant supervision of the cordless toll operator by locking the link switches of the channel or for indicating that this supervision is not required.

Call registrations were transferred to the marker from the class registers in the lower por tion of position circuit, Fig. 11, for indicating the class of the incoming trunk by operating relays 9! l, 9l2 or 9I3. The operation of relay 9|2 signals the marker that the calling incoming trunk is 2. via incoming trunk of the highest transmission characteristic. The operation of relay 9| I signals the marker that the calling incoming trunk is a terminal trunk. When relay 9H is energized the telephone connection may be extended either to a distant toll oflice and there terminated or it may be extended to a local ofiice in the area of this toll office. An incoming call over a via intertoll trunk may terminate in a local ofiice in the area of this toll ofiice. In this case relay 9| 2 will be energized to indicate an incoming call over a via intertoll trunk and also relay 9l3 will be energized by the coder registers to indicate the terminating area of the call. The energization of route relay 906, along with other apparatus not shown, is for a via connection to an intertoll trunk extending to another distant toll office. When the incoming intertoll trunk is a via intertoll trunk and the outgoing trunk is a via intertoll trunk the connection requires supervision and therefore the route relay energizes a class relay 908 which establishes a combined circuit for automatically looking a link between a position channel and the calling incoming trunk. This circuit, however, is not completed until the via out- 

